Biology 1111 Genetics & Molecular Biology Vocabulary

88 vocabulary flashcards covering key genetics and molecular biology terms from Biology 1111 Study Guide #5.

Monohybrid Cross

A genetic cross that tracks the inheritance of a single trait between two individuals.

Dihybrid Cross

A genetic cross that follows the inheritance of two different traits simultaneously.

F1 Generation

The first filial generation produced by crossing individuals from the parental (P) generation.

F2 Generation

The second filial generation, produced by interbreeding (or self-fertilizing) the F1 offspring.

P Generation

The parental generation in a genetic cross, whose offspring are studied.

Heterozygous

Having two different alleles for a given gene (e.g., Aa).

Homozygous

Having identical alleles for a gene (e.g., AA or aa).

Allele

An alternative form of a gene found at a specific locus.

Dominant Allele

An allele that masks the expression of another allele in a heterozygote.

Recessive Allele

An allele expressed only when present in two copies (homozygous).

Law of Independent Assortment

Mendel’s principle that alleles of different genes segregate independently during gamete formation.

Gregor Mendel

Austrian monk who discovered the basic principles of heredity through pea-plant experiments.

Incomplete Dominance

Inheritance pattern in which the heterozygote shows an intermediate phenotype.

Codominance

Inheritance pattern in which both alleles are fully expressed in the heterozygote.

Sex-Linked Trait

A trait controlled by a gene located on a sex chromosome (usually the X chromosome).

Phenotype

The observable traits of an organism.

Genotype

The genetic makeup of an organism for a particular trait or set of traits.

Test Cross

A cross between an individual of unknown genotype and a homozygous recessive individual to reveal the unknown genotype.

Dominant Disorder

A genetic disease expressed when only one copy of the mutant allele is present.

Recessive Disorder

A genetic disease expressed only in individuals homozygous for the mutant allele.

Lethal Allele

An allele that leads to the death of an organism when present in certain genotypes; often persists through heterozygous carriers.

Mutation

A heritable change in the DNA sequence.

Gametic Mutation

A mutation in cells that produce gametes; can be passed to offspring.

ABO Blood Types

Human blood groups determined by the IA, IB, and i alleles resulting in A, B, AB, or O phenotypes.

Antigen

A molecule on a cell surface that triggers an immune response.

Antibody

A protein produced by the immune system that binds specifically to an antigen.

Pleiotropy

A single gene influencing multiple, seemingly unrelated phenotypic traits.

Polygenic Inheritance

A trait controlled by many genes, producing continuous variation (e.g., height).

Sickle Cell Disease

A recessive disorder caused by a mutant β-globin allele leading to sickle-shaped red blood cells.

Huntington’s Disease

An autosomal dominant neurodegenerative disorder caused by a CAG repeat expansion.

Cystic Fibrosis

An autosomal recessive disorder due to CFTR mutations, causing thick mucus in organs.

Achondroplasia

An autosomal dominant form of dwarfism affecting bone growth.

Hypercholesterolemia

A genetic condition marked by high blood cholesterol, often autosomal dominant.

Pedigree

A family tree diagram that shows inheritance patterns of traits across generations.

Karyotype

An ordered photographic display of an individual’s chromosomes.

Linked Genes

Genes located close together on the same chromosome that tend to be inherited together.

Hershey–Chase Experiment

1952 bacteriophage study demonstrating that DNA, not protein, is the genetic material.

Bacteriophage

A virus that infects and replicates within bacteria.

Virus

An infectious particle consisting of nucleic acid enclosed in a protein coat; requires a host cell to replicate.

DNA

Deoxyribonucleic acid; the double-stranded molecule that stores genetic information.

RNA

Ribonucleic acid; usually single-stranded, involved in protein synthesis and regulation.

Complementary Base Pairing

Specific hydrogen bonding between A–T (or A–U) and G–C nucleotides.

Watson and Crick

Scientists who proposed the double-helix model of DNA structure in 1953.

DNA Polymerase

The enzyme that synthesizes new DNA strands by adding nucleotides to a template.

Transcription

The synthesis of RNA from a DNA template by RNA polymerase.

RNA Polymerase

The enzyme that builds RNA using a DNA template.

Translation

The process in which a ribosome synthesizes a polypeptide using mRNA codons.

Template Strand

The DNA strand that serves as the pattern for RNA synthesis.

5′ to 3′ Direction

The orientation in which nucleic acids are synthesized and read.

Initiation

The first stage of transcription or translation in which the machinery assembles and begins synthesis.

Elongation

The stage of transcription/translation where the strand or polypeptide is extended.

Termination

The stage where synthesis stops and the newly made molecule is released.

mRNA

Messenger RNA; carries genetic information from DNA to the ribosome.

tRNA

Transfer RNA; brings specific amino acids to the ribosome based on its anticodon.

rRNA

Ribosomal RNA; forms the core structure and catalytic sites of ribosomes.

Okazaki Fragments

Short DNA segments synthesized on the lagging strand during replication.

DNA Ligase

An enzyme that joins DNA fragments by forming phosphodiester bonds.

Helicase

An enzyme that unwinds the DNA double helix during replication.

Reverse Transcriptase

A viral enzyme that synthesizes DNA from an RNA template.

Codon

A three-nucleotide mRNA sequence that specifies an amino acid or stop signal.

Anticodon

A three-nucleotide sequence on tRNA complementary to an mRNA codon.

Intron

A non-coding sequence in a primary RNA transcript that is removed during splicing.

Exon

A coding sequence that remains in the mature mRNA after splicing.

5′ Cap

A modified G nucleotide added to the 5′ end of eukaryotic mRNA for stability and ribosome binding.

Poly-A Tail

A chain of adenines added to the 3′ end of eukaryotic mRNA for stability and export.

Ribosome

A complex of rRNA and proteins that synthesizes proteins by translating mRNA.

E Site

The ribosomal site from which empty tRNA exits.

P Site

The ribosomal site holding the tRNA with the growing polypeptide chain.

A Site

The ribosomal entry site for aminoacyl-tRNA carrying the next amino acid.

Prokaryotic Ribosome

The 70S ribosome found in bacteria; target of many antibiotics.

Eukaryotic Ribosome

The 80S ribosome found in the cytoplasm of eukaryotic cells.

Point Mutation

A change in a single nucleotide pair of DNA.

Frameshift Mutation

An insertion or deletion that alters the reading frame of a gene’s codons.

Silent Mutation

A nucleotide change that does not alter the encoded amino acid.

Mutagen

A physical or chemical agent that increases mutation rate.

Carcinogen

A mutagen that can cause cancer.

Termination Codon (Stop Codon)

mRNA codons UAA, UAG, or UGA that signal the end of translation.

Genetic Code Redundancy

Feature of the genetic code in which multiple codons specify the same amino acid; the code is degenerate but unambiguous.

Alternative RNA Splicing

Process in which different combinations of exons are joined to produce multiple mRNAs from one gene.

Deletion Mutation

Loss of one or more nucleotides from DNA.

Insertion Mutation

Addition of one or more nucleotides into DNA.

Inversion Mutation

Reversal of the orientation of a DNA segment within the chromosome.

Substitution Mutation

Replacement of one nucleotide with another in DNA.

R-Plasmid

A bacterial plasmid carrying genes that confer antibiotic resistance.

Promoter

A DNA sequence where RNA polymerase binds to initiate transcription.

Semi-Conservative Replication

DNA replication mechanism in which each daughter molecule has one old strand and one new strand.

Purine

A double-ring nitrogenous base (adenine or guanine).

Pyrimidine

A single-ring nitrogenous base (cytosine, thymine, or uracil).